title: Suppression of Glutamine:fructose-6-phosphate amidotransferase-1 inhibits adipogenesis in 3T3-L1 adipocytes.
abstract: O-linked N-acetylglucosamine (O-GlcNAc) protein modification has been implicated in the regulation of signaling pathways, cell function, and gene expression. Glutamine:fructose-6-phosphate amidotransferase-1 (GFAT-1) is the rate-limiting enzyme in the hexosamine biosynthetic pathway (HBP), which generates the sugar nucleotide UDP-GlcNAc, where this nucleotide acts as the donor for O-GlcNAc modification. In this study, we determined whether GFAT-1 regulates adipogenesis in adipocytes. 3T3-L1 preadipocytes were differentiated using medium containing high glucose, insulin, dexamethasone, and isobutylmethylxanthine. Cells were harvested 4, 8, and 12 h and 1, 2, 3, 4, 6, and 8 days after the initiation of differentiation. Global level of O-GlcNAc modification increased 4 h after induction and persisted for 8 days of observation. GFAT-1 mRNA and protein expression was also upregulated beginning 4 h after induction. Pharmacological inhibition of GFAT-1 or GFAT-1 siRNA treatment blocked the increase in O-GlcNAcylation and the formation of lipid droplets in adipocytes. GFAT-1 may regulate the expression of C/EBPβ, PPARγ, SREBP-1, fatty acid synthase, S3-12, perilipin, or adipophilin during adipogenesis. Our results suggest that GFAT-1 plays a critical role in modulating adipogenesis via the regulation of protein O-GlcNAcylation in adipocytes.
authors.affiliation: Department of Medical Genetics, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.
authors.forename: Tusty-Jiuan
authors.initials: TJ
authors.lastname: Hsieh
authors.forename: Tzu
authors.initials: T
authors.lastname: Lin
authors.forename: Pei-Chen
authors.initials: PC
authors.lastname: Hsieh
authors.forename: Min-Chun
authors.initials: MC
authors.lastname: Liao
authors.forename: Shyi-Jang
authors.initials: SJ
authors.lastname: Shin
mesh_terms: D000107:Acetylation; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D050156:Adipogenesis / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D015870:Gene Expression / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology*; D005973:Glutamine / Q000378:metabolism; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing); D047468:Immunoprecipitation; D051379:Mice; D019884:Nitrogenous Group Transferases / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000502:physiology; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D005973:Glutamine; D019884:Nitrogenous Group Transferases; C488523:Gfpt1 protein, mouse; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing)